This test measures the levels of cardiac biomarkers – enzymes, hormones, and proteins – in your blood.
Cardiac biomarkers appear in your blood after your heart has been under severe stress because it isn't getting enough oxygen – for example, if you've had a heart attack. The levels of biomarkers are often used to quickly determine the size of an attack and how seriously your heart was affected.
These cardiac biomarkers can be used to diagnose a heart attack:
Cardiac troponin, a protein, is by far the most commonly used biomarker. It has the highest known sensitivity and enters into your bloodstream soon after a heart attack. It also remains in your bloodstream days after all other biomarkers return to normal levels.
Creatinine kinase (CK), an enzyme, can also be measured several times over a 24-hour period and will usually at least double if you've had a heart attack. But because CK can increase in many other conditions besides a heart attack, it is not very specific.
CK-MB is a subtype of CK. It is more sensitive for heart damage from a heart attack. CK-MB rises four to six hours after a heart attack but is generally back to normal within a day or two. Because of this, it's not helpful when a doctor is trying to figure out whether your recent chest pain was a heart attack.
Myoglobin is a small protein that stores oxygen and is measured occasionally. Myoglobin is sometimes measured in addition to troponin to help diagnose a heart attack.
You might need this test if your doctor suspects you're having or have recently had a heart attack or if you have symptoms of coronary artery blockage.
Symptoms of coronary blockage may include:
Chest pain or pressure that lasts for more than a few minutes
Pain or discomfort in your shoulders, neck, arms, or jaw
Chest pain that increases in intensity
Chest pain that's not relieved by rest or by taking nitroglycerin
Other symptoms that may happen along with chest pain:
Sweating, cool, clammy skin, or paleness
Shortness of breath
Nausea or vomiting
Dizziness or fainting
Unexplained weakness or fatigue
Rapid or irregular pulse
Your doctor may order other tests to measure other factors in your blood. These include:
Blood gases or other tests to measure oxygen in the blood
Complete blood count
Electrolytes (sodium, potassium, chloride)
Blood fats (cholesterol and triglycerides)
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Results are given in nanograms per milliliter (ng/mL). People who are young and healthy usually have little or no cardiac troponin in their blood.
Normal-level results vary, but people with levels of cardiac troponin at or above 0.01 ng/mL are twice as likely to have life-threatening cardiac disease.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Other factors aren't likely to affect your results.
You don't need to prepare for this test. But be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.